Streptococcus mutans plays a significant role in dental caries. LTAs from cariogenic and non cariogenic bacteria may have different physico-chemical properties which can lead to different immunogenic characteristics. Our knowledge of living organisms has now reached a state of development where the fundamental unit of biological study is the molecule rather than the cell, thus shifting biology to a molecular or chemical science. The biological properties exhibited by macromolecules are not only due to their chemical composition and configuration but also to their physical and conformational properties. The extraction, immunological properties, biological properties and biosynthesis of LTAs have been extensively investigated. In contrast to this, little is known concerning the physico-chemical nature of the LTAs. Therefore, it is the overall specific aim of this project to obtain definitive data on the physico-chemical parameters of the LTAs. The LTAs and deacylated moiety extracted from cariogenic S. mutans Ingbritt and BHT from non-cariogenic S. pyogenes, and S. faecalis ATTCC 8790 from cellular and extracellular sources, will be examined from solution, using the methods of small angle x-ray scattering, sedimentation analysis and viscometry. These measurements will provide information on their shape and size. e.g. molecular weight, radius of gyration of the molecule and its cross-section, mass per unit length, hydrodynamic volume, persistence length etc. Long term objective is to compare the physical and conformational properties of the LTAs obtained from various pathogenic and non-pathogenic bacteria and to correlate these findings to their pathogenicity and immunogenicity.